Hemispheric annealing and lateralization under psychedelics (HEALS): A novel hypothesis of psychedelic action in the brain.
Journal of psychopharmacology (Oxford, England) – May 01, 2025
Source: PubMed
Summary
Psychedelics may reverse the typical dominance of the left hemisphere in brain function. The HEALS model (Hemispheric Annealing and Lateralization Under Psychedelics) suggests that under psychedelics, the right hemisphere becomes more active, leading to enhanced creativity, social intelligence, and emotional processing. Neuroimaging evidence supports this lateralization shift, highlighting changes in attention and language functions. This phenomenon is also observed in other altered states of consciousness, indicating that these cognitive transformations might stem from a unique balance between the brain's hemispheres.
Abstract
Current models of psychedelic action in the brain propose changes along the dorsal-ventral and anterior-posterior axes but neglect to address the lateral axis. This article proposes a novel model of psychedelic action called HEALS (Hemispheric Annealing and Lateralization Under Psychedelics) which involves the reversal of the typical hierarchical relationship between the two hemispheres of the brain. In typical modes of consciousness, the hemispheres act in parallel process with the left predominating. Under psychedelics, as well as in other altered states of consciousness (ASCs), this hierarchy is reversed, with the right hemisphere released from inhibition by the left. In support of this model, the available neuroimaging evidence for lateralization under psychedelics is reviewed. Then, various cognitive and emotional changes observed under psychedelics are contrasted with those same functions in each hemisphere. These include attention; social and emotional intelligence; creativity and insight; and language. The article concludes with a review of laterality in other ASCs, such as meditative and trance states, and suggests that many phenomena associated with psychedelics, and other ASCs, might be explained by an atypical annealing between the hemispheres toward right hemisphere predominance.